Getting into this price range can really begin to open up the possibilities for you to find real relief. Typically the best air purifiers in this price range can clean larger volumes of air which is important to their effectiveness. They may also offer a better build quality and may potentially offer more in terms of extra features.
The Austin Air Healthmate features one of the best HEPA filters on the market with a long filter life and many pounds of activated carbon/zeolite for odors and harmful chemical gases.
The Blueair 403 is capable of trapping very small particles with great efficiency and offers 3 lbs. of activated carbon with the ability to clean large spaces.
The Winix 9500 offers several filtration technologies which help battle anything from allergens to odors and even viruses. There are a handful of luxury convenience features included and it all comes at an exceptional value.